1. Field of the Invention
The present invention relates to an irradiating conveyance apparatus for irradiating radiation such as an electron beam to a preform of synthetic resin product, in particular, as acrylonitrile resin product while the preform is transferred to prevent to prevent monomers from remaining in such a synthetic resin product.
2. Prior Art
Hitherto, it has been known that when containers or bottles made of synthetic resin, in particular, acrylonitrile resin, are filled with a content such as a beverage, monomers retained in the synthetic resin material are extracted into the content and as a result the quality of the content changes to have a strange taste and to become harmful for the health and safety of persons.
It is well known to irradiate an electron beam to a preform of a synthetic resin product in order to remove the harmful monomers as described in Japanese Patent Publication Nos. 5654321 and 62-47689.
Japanese Patent Publication No. 62-47689 concretely discloses an apparatus for irradiating the electron beam. Such an apparatus includes a truck provided with a plurality of rotary plugs mounted thereon and each adapted for fitting a neck portion of the preform thereto, and an electron beam accelerator positioned above a path of the truck. The truck is advanced along the path while the plugs are rotated to rotate the preforms to thereby irradiate the electron beam from the electron beam accelerator to the advancing and rotating preform. The reason why the truck is advanced is that all the preforms are to be passed through an electron beam irradiation area directly under the electron beam accelerator and the reason why the preform is rotated is that the inside of the preform is to be effectively and uniformly irradiated by the electron beam of which penetrating power is not high.
The known irradiating conveyance apparatus mentioned above has disadvantages in that fitting of preform is not easy and the plug does not have interchangeability since only preforms having at least the same neck portion of the same diameter can be treated and consequently the productivity is very low. That is, since the attachment of the preform is effected by fitting the neck portion of the preform into the plug, it is necessary to individually attach each preform to each plug by hand and also to individually detach each preform from each plug by hand after irradiation, and further a preform having a different diameter of the neck portion cannot be attached to the same plug. Therefore, when preforms having neck portions of a different diameter are treated, it is required to perform such a troublesome work that all the plugs are exchanged.